thank for sharing your concern usually the symptoms of common flu last less than a week but in many cases the cough, may last for more than two weeks.the fatige may last for nearly ten days so you need nearly two weeks to pas all the symptoms of flu.you need to use a lot of water healthy foods like fruits vegetable avoid smoke and cigarette you may use nurofen if you feel pain in muscles be careful to use C vitamins if you have the same symptoms after two weeks is important to take contact with your doctor may be your flu is complicatet and there you need a treatment with antibiotics all the best